Gyrating rotary bit



7 Dec. 31, 1940.

J. A. ZU BLlN GYRATING ROTARY BIT Filed Oct. 10. 1939 ing.

Patented Dec. 31, 1940 FFICE GYRATING ROTARY BIT, John azutun, Los Angeles, Calif. Application October 10, 1939, Serial No. 298,779

11 Claims. (01. 255-71) This invention relates to well drilling equipv ment, and more particularly to bits for the rotary drilling-of oil wells.

In my patented bits, for example, those in United States Letters Patent numbered 1,859,- 948; 2,025,260; and 2,113,820, I have shown a type of construction for bits in which the cutter is rotatably mounted upon the shank at an angle to the axis of the shank and the hole being made, so that, upon the rotation of the shank, the cutter takes a sort of combination rotating and oscillating movement through the formation. The teeth of the cutter engage the material being cut and tear it loose, after which the loosenedmaterlal is carried to the surface by the rotary mud flowing down the drill pipe and up the hole.

As will be clear uponinspection of my patented device, the action of the teeth of the cutter upon the formation involves a large component of vmovement tangential to the formation after the teeth have penetrated. Although advantageous in many types of formation, this tangential component of motion causes excessive wear upon the teeth in cutting very hard formations, as the penetration may be insufficient to split off the formation sufficiently to prevent the teeth'from dragging across the formation;

As actually made, the teeth of my cutters (me made in different shapes and positions, for

ferent formations, in eflect lessening the drag to a certain extent by shortening the "stroke" of, the cutter, but there is a definite limit to the progress which can be. made in that direction. The chief .cause of this limitation is the shape 'of the cutter body- The shape at present used is necessarily utilizedbecause of the internal bearing structure involving a thrust cone and pin, of necessity of certain definite dimensions to transmit the large forces developed in drill- Inasmuch as the drilling of-hardformatlon involves the utilization of a more nearly true rolling motion of the bit in the formation, it becomes a primary object of my invention to lessen the drag of the teeth across the forma tion.v

vide an internal construction which will not interfere with the attainment of a shapeandposition of the cutter rolling motio'n. 1

Itis a further object of my invention to pr duce a bit which will tend to always produce a full gauge hole.

to give a more nearly pure the bit, between the It is a further object of my invention to pro- Briefly, what f'propose to do is to in effect change the bearing surfaces of the cutter shown in my patented bits, and at the same time change the external configuration of the cutter so as to give more nearly a pure rolling motion.

Another limitation upon the action of the cut- 5 ters is the circulation of the rotarymud at the bottom of the hole. Modern drilling practice demands that. there be a largecirculation of liquid down the drill pipe and up the bore of the hole, to carryoif the cuttings detached from the formation. The most eiilcient circulation is that which is most rapid close to the cutting teeth, in order that the teeth engage a clean surface, and that they work upon unbroken formation, instead of pulverizing and breaking material already broken loose from the formation. Inasmuch as the size of the particles which may be carried by a fluid stream is dependent upon the velocity of .the stream, a high velocity at the point being cleaned is desirable. Attainment of high velocity is most easily accomplished by the use of channels of definite dimensions, which can be made the right size to give any desired velocity.

Inasmuch as the velocity of the fluid past the formation,'rather than'the velocity of'the fluid issuing fromthej nozzle, is the factor which determines the effectiveness of the fluid inclearing the hole of detritus, broken loose from the formation, it becomes another object of my invention to provide definite channels, one of the walls of which is the formation itself, 'forthe passage of the drilling'fluidf from the discharge opening of the bit to the annular space above walls of the hole being drilled and the drill pipe.

An important function of. the fluid issuing from the bit is-the cleaning of theiteeth of the cutter. Here the velocity of the fluid past the teeth is the important factor in an efficacious cleaning of theteeth. It'thu's becomes a still further object of my invention to provide means for'the directing of the fluid Referring to the figures:- Figure 1 is a diagram illustrating'the principle of my invention. a

Figures 2 and 3- are'sections of bits embodycog ing my invention."

' -Flgure.4 is a bottom view-of acutter.

- Referring to Figure 1, a cutter 4 is more or less ditically illustrated; This te is 1 torotate about axis 5-. and the axis H roj'tates about the of the hole: During issuing from the" nozzle'directly' along the teeth. I

- matter what action takes place. the elements of this rotation, there are several actions of the cutter on the formation, which will-be apparent from the following considerations.

If the cutter were shaped so that the bottom were a cone, or a plane, with apex or center, respectively, at the intersection of 5-5 and H, it would travel about a conical surface with a true rolling motion. As can be seen from the drawing, the cutter is not so shaped. It has portions extending above and below the line representing the true rolling motion line. This being so, the cutter has all points below the line of true rolling motion slipping on the formation, in a forward direction. All'points above the true rolling motion line slip backwards on the formation.

In addition to the motion of the teeth over the formation described, there is a radial slip caused by the pre'ssureof theside walls upon the reamer teeth at the surface 8 of the cutter. The cutter. always, as a general principle, tries to ut as small a hole as possible, and there is no p ssure tending to move the cutter to the left in the drawing except the component in that direction caused by the reaction of the bottom of the hole upon the part of the cutter in contact therewith.

The shape of the bottom of the hole and the sides of the hole can be adjusted by properly designing and spacing the teeth on the bottom and sides so that the cutter can produce an oversize hole. The less sliding towards the center of the lowermost part of the cutter there is, the closer will the cutting of the bottom approach true rolling. In order to lessen this sliding, to a certain extent, and to put it to good use, I have illus- .trated the bottom'of the cutter as having a sort of cuspate configuration, with the result that it cuts the formation into a sharply cusped form, as shown in Figure 1. It is possible, by this means, to limit the sideways sliding of the cutters, by making the resultant of the weighton the bit and the side thrust of the wall take a direction normal to the part of the cutter in formation contact. In such case, the side thrust, instead of sliding the teeth of the cutter over the formation, will cause them to penetrate, and pieces of the formation will be broken out upon rotation of the bit body because of the non-rectilinear configuration of the elements of the teeth.

Of course, it may well be that the side thrust of the cutter on the cusped bottom of the hole will break off the sharp point of the hole bottom, which is an advantage as the tendency is, due

to the low linear velocity of the cutter with respect to the formation near the center of the cutter, for the center to be inefllcient as a cutting element.

It is to be borne in mind, however, that no the cutter surface 8 perpendicular to the paper in the drawing are also perpendicularto the axis of the hole, and if nothing else does, will ream the hole to gauge. r

With the above in mind, the reasons for the constructions illustrated in Figures 2 and 3 become apparent.

In Figure 2, 9 represents a shank with apin for connection with the drill collar, with the watercourse It therethrough for thecirculating fluid.

The shank is curved, and so arranged to give a generally circular bottom portion inclined to the shank axis. Fastened to the bottom of the shank on the inclined portion is a bushing H, which .may be threaded or-otherwise secured to the shank. This bushing has one or more races, l3,

l4, to take balls I! forming a thrust bearing for the cutter. 1

The vcutter is a sort of mushroom shaped piece of metal, with a stem l6 and head l'l, furnished with teeth 18, the head and stem being bored 15 for a continuation of the watercourse, and the head being furnished on the upper side with a race or races I9, 20, to correspond with those of the bushing.' Around the stem is a series of rollers 2|, running in a portion of reduced, diameter 10 of the stem.

Somewhere in the stem, here illustrated at the top, is a ball race 22, containing balls 23 running in the shank and the race. The races are preferably in the shank itself, rather than in the bushing, for ease of assembly and to lock the cutter completely, in case of failure of the bushing. The balls 23 .are inserted through a hole 25, closed by a plug, in the shank, or in any other conventional manner. In Figure 3 I have illustrated another form of my invention. In this form, everything lsas in Figure 2, except that an additional race is provided on the circumference of the bushing for the r cutter bearings '21. The purpose of this form as 25 distinguished from that of Figure 2 is to prevent the exertion of too great bending strains on the cutter stem in the event that the cutter is subject to loads tending to force the cutter off the shank, as when attempting to drill upwards through a cave in the hole, or in a like situation.

In connection with both Figures 2 and 3, attention is invited to the formation of the watercourse through the cutter stem and head. At the exit end of the watercourse, the watercourse is partly covered with the teeth which extend thereover, and a deflector vane is fastened to those teeth. This vane is generally circular, as shown in Figure 4, and the side towards the watercourse is of a cross-shaped aspect, filling the bore in the head, and providing four passageways arounditself. which provide an exit for the drilling fluid tangential tothe outer face of the cutter. The fact that the line of actlonof the discharge is straight, and cannot follow the curve of the cutter, is of no consequence, because the issuing stream in effect expands, due'to its viscosity and elfecton the fluid through which it travels. In

impinging against those teeth in formation con- 5 tact it is guided along the formation-in the channels formed between the teeth'and the formation, thus clearing away the broken material from the surface of the formation, travelling at sufflcient velocity, because of the restricted channel, as to do so. x

It is to be understood that variations in the constructioh may be resorted to within the. scope of the appended claims..

What -I claim as my invention is; so

1. In a device for drilling wells. comprising a curved shank with a watercourse therein,'and a cutter mounted so as to be rotatable about its axis at an angle to' the axis of rotation of the shank, the combination of a bore in the shank in alignment with the'watercourse, a hollow stem on the cutter, radial and thrust hearings on the stem of the cutter between the cutter stem andthe bore of the shank, and thrust bearings between the head of the cutter and. the shank for transmitting axial loads from the head to the shank. 4

2. In a device for drilling wells, comprising a cutter rotatably mounted on a shank to rotate at an angle to the axis .of rotation of the shank,

said cutter having a surface with the axis of the cone coinciding with the axis of the cutter; the combination of a stem on the cutter, a bore in the shank taking the cutter stem, a pair of races betweenthe stem and the bore of the shank, and a pair of races between the cutter head and the shank, whereby axial and radial loads on the cutter may be transmitted to the shank.

3. In a device for drilling wells, comprising a cutter having a stem and rotatably mounted on a shank to rotate at an angle to the axis of rotation of the shank, said cutter having a conical surface with the axis of the cone coinciding with the axis of the cutter; the combination of a ball bearing between the shank and the cutter stem, a roller bearing between the cutter stem and the shank, and ball bearings between the shank and the cutter head.

4. The device of claim 3, in which one of the bearings between the cutter head and the shank is arranged to run on a periphery of the shank.

5. An assembly for a well drilling bit comprising a shank, a cutter with a stem and head, the stemand head having an axial bore to form a passage for the drilling fluid, and a bushing secured to the shank, said stem having races therein for the accommodation of bearings, and said bushing having a race for the accommodation of one set of bearings for the stem, and a race in the shank for the accommodation of another set of bearings, whereby the bushing and the shank are prevented from separating by the engagement between the stem shank through the bearings therebetween.

6. The device of claim 5, with an additional bearing capable of withstanding axial loads between the cutter and the bushing.

7. In a well drilling bit, a hollow bushing extending into the bore of the shank and across the end of the shank, ball races in the shank'and the bushing, and a cutter with a stem having races to correspond with the races in the shank and the bushing, the races in the stem containing bearings preventing axial movement of the of the cutter andthe bushing with respect to the shank, and the other races transmit g loads from the cutter to the bushing.

8. In a device for drilling wells, a shank, a cutter rotatably mounted thereon at an angle thereto, said cutter having'an axial hole therethrough for the discharge of fluid from the cutter, and deflecting means extending across the circulation hole of the cutter and spaced downwardly below the mouth of the hole causing the fluid to discharge substantially tangentially to the face of the cutter.

9. A cutter, for a bit for drilling wells, with an axial hole therethrough for the discharge of fluid for clearing the hole of cuttings and cleaning the teeth of the cutter, vanes on the cutter and extending across the axial hole and below the discharge end thereof for directing the fluid in a direction substantially tangentially of the surface of the cutter.

10. A cutter, for a bit for drilling wells, hav

ing an axial circulation hole therethrough, teeth extending across the face of the cutter, some of the teeth extending across the axial hole of the cutter, and varies formed by the inner faces of the teeth for distributing the circulation fluid radially of the cutter axis as it emerges from the circulation hole, whereby the circulation fluid washes substantially tangentially across the face of the cutter.

11. A rotatably mounted cutter, for a bit for drilling wells, having an axial circulation hole therethrough, radial teeth on the face of the cutter, and means on the cutter below the circulation hole and lying inthe path of flow of circulation fluid forced through the cutter for deflecting the discharge of circulation" fluid sub-. stantially tangentially to the face of the cutter, whereby some of the fluid passes through the space formed by the radial teeth and the formation at high velocity, and some of the fluid travels tangentially across the teeth of the cutter not in formation contact.

. JOHN A. 

